Measurement of TFT/LCD flicker for ISO compliance

Flicker is one of the major concerns in the design of computer display, and there have been many research reports on measuring and predicting flicker in order to provide users with flicker-free displays. Most of the previous studies, however, have been based on CRT displays. In this study, flicker on a thin-film transistor liquid crystal display (TFT/LCD) was measured by using a subjective evaluation method. The purpose of the study was to ascertain whether the TFT/LCD conform to ISO standards on flicker, and to determine the main factors affecting flicker on the TFT/LCD. The results indicate that the TFT/LCD used in the study met the ISO standards at frame frequency as low as 35 Hz when all-pixels-on patterns were displayed. It was found that the common voltage (Vcom) is one of the most important factors affecting flicker on the TFT/LCD, and that the Vcom should be well-balanced to make the TFT/LCD flicker-free. It was also found that the analytic method proposed in ISO/CD 13406-2 was not always appropriate for predicting flicker on the TFT/LCD.